Park in lay-by 20.
As is often the case in Scotland the road, river and railway all converge here. You passed over the Jubilee Bridge just before this lay-by then immediately crossed the railway although it is not too obvious that you are going over a railway tunnel.
It is possible to walk back from here (be VERY careful between lay-by & bridge although the verge is quite wide) turning down right (before the Jubilee Bridge) through two gates. Immediately after the second gate the fence is down so you can turn left through the trees down tho the path by the river (about 50m) for a circular walk down to Dunkeld with several caches to be picked up en route. Alternatively you can go down the edge of the field to pick up the footpath but it seems to be a bit overgrown at the moment. You would come back just North of the Jubilee Bridge. It is a fair way though (about 4.5 miles) so you would need lots of time and a bit of research before tackling this.
If you are lucky you may see deer grazing in the field between the road and railway.
You are looking for a small lock N lock box in a cammo bag.
Cache box has some swaps and room for small trackables or coins. Note the 'bean' pen is not a swap and stays with the cache.